Page:The American Cyclopædia (1879) Volume VI.djvu/708

 696 EPIZOA Head Louse (Pediculus capitis). females. The eggs, which are bean-shaped, cling to the hair as soon as laid, probably by means of some glutinous matter secreted by the female. After remaining as nits for 6 days, the young emerge, and at the end of 18 days more are capable of reproducing. Each female can deposit 50 eggs in all. The pres- ence of lice is easily detected, for we may see them with the naked eye, and their eggs attached to the ends of the hair can- not escape detection. Even when the old are at work beneath the disgusting disease they create, the fe- males creep forth to deposit the nits upon the fine ends of the hair, perhaps because too great heat is prejudicial. A mere itch- ing is the first symptom of lice, which leads in simple cases to scratching and slight excoriations of the scalp. Let heads so in- fested remain for months uncombed and un- cared for, and such cases will result as are often seen in European hospitals. A specimen is brought in with hair all matted together in flakes, and looking as if sand and molasses had been poured upon it and dried. The stench is loathsome and sickening. On raising the hair a frightful mass of filth, pus, scabs, and lice is visible. The scalp is found covered with crusts of blood, with open ulcerating sores, and with thick and elevated scabs, from beneath which on pressure pus flows freely. The ears, too, may be converted into a suppurating surface. The P. vestimenti, or body louse, is much larger than the preceding species. The head is longer, and its color dirty white. This ani- mal is seldom if ever found on the body, but inhabits the seams and folds of clothing next the skin, where, it deposits its eggs. Its bite causes the same itching as that of the P. capi- tis, but the results are different. The scratch- ing brings on papules, which become excori- ated, and eczema appears. The clothes adhere to the skin, which brings on exudation, and lastly pustules appear. In some cases constant scratching produces such a hyperaemia that a deposition of pigment follows sufficient to color the whole skin like that of the negro. The P. tdbescentium of writers has longer antennae and a larger and more distinctly separated thorax than the two preceding species, and an indistinctly ringed abdomen. It inhabits the skin itself, living in its fold beneath the epider- mis, and produces the disease called phthiria- sis. Leeuwenhoeck cultivated a colony on his own leg for a considerable time, and estimated that in eight weeks one female might become the grandmother of 5,000. But some of the best authorities deny the existence of any such species. The phtMrius pubis is considerably broader, and has a shorter posterior extremity, than its relatives. Its legs are long, and the hindermost two are armed with immense claws. It is very slow in its motion, and has no eyes. This species, as its name implies, is found most Phthirius pubis. frequently on the pubes, but occasionally on the beard, eyebrows, and hair of the breast and axillae, where it bites deeply into the skin, and lives upon the blood of its host. "When present in numbers, these parasites cause an intolerable itching, and may be seen sticking firmly to the surface of the body like black specks of coal. Kilchenmeister has found on the heads of an Egyptian mummy and a New Zealand savage nits whose claws differ some- what in size from those of the ordinary species. Lice are a world- wide pest, and no nation seems free from them. According to Aristotle, they must have been a great plague among the ancients, and Alcman, Sulla, and Philip II. are reported to have died of them. But it is prob- able that some other parasite, as the mites, was confounded with them. Rising a step higher among the insects, we come to the hemimeta- ~bola, or those with an incomplete metamor- phosis. In the order hemiptera we find the cimex lectularius or acanthia lectu- laria. The bed- bug has a small head, from which project two long three-jointed an- tennae. Behind the compound eyes are two small trans- parent flaps cov- ered with bristles, which are the ru- diments of wings. The thorax is broad and short, the abdominal segment very large, broad, and flat. The eggs are long and cylindrical, and are furnished with a stem, by which in the spring the female fixes them upon objects. It is of a reddish brown, and has a very disagreeable odor, which arises from two Bedbug (Cimex lectularius).